1. Field of the Invention
The invention relates to a touch display device. More particularly, the invention relates to an optical touch display device.
2. Description of Related Art
The increasing progress of display technologies brings about great conveniences to people's daily lives, and the demands for light and compact display devices contribute to the development of flat panel displays (FPDs) as mainstream displays. Among various FPDs, liquid crystal displays (LCDs) characterized by great space utilization, low power consumption, non-radiation, and low electromagnetic interference are prevailing.
With advancement of information technology, wireless mobile communication, and information appliances, input devices of various information products including conventional key boards or mice have been replaced by touch panels in order to comply with requirements for portability, compactness, and user-friendly interfaces, and the touch panels are integrated with displays to form touch display devices. At present, the touch panels can be generally categorized into resistive touch panels, capacitive touch panels, optical touch panels, acoustic wave touch panels, electromagnetic touch panels, and so on. Since the touch-sensing mechanisms of the optical touch panels are suitable for the large-sized display panels, the display panels with large size often achieve the touch-sensing function by applying the optical touch-sensing mechanisms.
FIG. 1A is a schematic cross-sectional view illustrating a conventional LCD. With reference to FIG. 1, the LCD 100 includes a device housing 110 and a liquid crystal display module (LCM) 120, and the LCM 120 is configured within the device housing 110. In general, the LCM 120 is formed by assembling a front bezel 121, an LCD panel 123, a frame 125, an optical thin film 127, a light guide plate 129, a backlight source 131, and a back bezel 133. However, the display surface of the LCM 120 and the surface of the device housing 110 are not at the same horizontal level, which poses a negative impact on visual effects.
FIG. 1B is a schematic cross-sectional view illustrating a conventional touch display device. With reference to FIG. 1B, in the touch display device 101, an optical touch module 140 is configured between the device housing 110 and the LCM 120. The optical touch module 140 includes a light source 141, a photo sensor 143, and a reflector 145. However, after the optical touch module 140 is additionally formed in the touch display device 101, the level difference between the display surface 120D of the LCM 120 and the surface 110S of the device housing 110 becomes more significant, which further leads to unpleasant visual effects.
FIG. 1C is a schematic view illustrating a back bezel in a bent state or not in a bent state in a conventional optical touch module. With reference to FIG. 1C, the optical touch module 150 includes a light source 151, a photo sensor 153, and a back bezel 155. When the back bezel 155 is not bent yet, the photo sensor 153 can receive light from the light source 151, and the light receiving range of the photo sensor 150 is between the straight line L1 and the straight line L2. After the back bezel 155 is bent, the light source 151 is located beyond the light receiving range of the photo sensor 153, such that the photo sensor 153 is unlikely to receive the light from the light source 151, and that erroneous touch points are detected.